Skin irritation is caused by a wide range of conditions, including allergies, medication, cosmetics, and diseases. Skin irritation results in a rash, which is a visible change in the color or texture of the skin. The skin may become red, itchy, bumpy, chapped, flaky, with hives, or otherwise irritated.
Inflammation of the skin is known as dermatitis. Contact dermatitis is a common cause of skin irritation. Contact rashes occur upon a contact with an agent that causes a reaction. Such agents include, but are not limited to, cosmetic and beauty products, drugs and medications, soaps, detergents, dyes (e.g. in clothing), metals (e.g. nickel in jewelry), chemicals (e.g. in rubber, elastic, or latex), poisonous plants (e.g. poison oak, poison ivy, or poison sumac), environmental toxicants, irritants of botanical origin (e.g. plant parts and plant extracts), irritants of marine origin (e.g. “red tide” or excessive algae bloom), urine and fecal irritants (e.g. agents that induce diaper rash), minerals, transdermal delivery agents and devices (e.g., agents that transfer active ingredients through the skin into the bloodstream such as creams, ointments, lotions, sprays, gels and the like, or devices like microneedles, patches, ultrasound devices, iontophoresis devices and the like), adhesives, foods and other irritants. The contact with, or exposure to the irritating agents could be accidental, or expected, and could be of a single event or multiple, or repetitive events.
Irritant contact dermatitis from plants could be induced mechanically or chemically. The common mechanical plant irritants include thorns, spines, glochids, trichomes, and sharp-edged leaves. Many plant-based chemical irritants are unknown yet, but known agents include calcium oxalate, protoanemonin, isothiocyanates, bromelain, diterpene esters, alkaloids, and other chemical irritants such as naphthoquinone and acids.
Diaper rash (diaper dermatitis) is the persistent compromise of the epidermal barrier, at the macroscopic or microscopic level, with or without infection (e.g. C. albicans). The initial stage of diaper rash is induced by contact with digestive enzymes that are present in infant feces, and in particular chymotrypsin. It is further exacerbated by the skin irritating activity of other fecal and urine enzymes, wetness (including diaper hydration and diaper friction), with the possible additional irritation by microbial and fungal agents.
It is desired to provide a prophylactic treatment i.e. to reduce the severity of or to eliminate skin irritation induced by a contact with an irritating agent. It is also desired to provide a treatment to reduce the severity of or to eliminate skin irritation induced after a contact with a skin irritant.
Topical preparations are used to treat skin with a need and provide health and cosmetic benefits thereto. Topical agents include topical medications and skin care products in such forms as balms, creams, gels, oils, lotions, patches, ointments, sprays and the like. They contain an active ingredient with a desired activity, and excipients, which may include e.g. thickeners, preservatives or fragrances. Numerous topical formulations are prescribed by physicians, while many others are available over-the-counter and as cosmetics (e.g. antibacterial and antifungal preparations, anti-inflammatory and pain-relief preparations, cleansing and moisturizing agents, and beautifying and anti-aging agents). Unfortunately, some of these topical preparations induce adverse or undesirable effects such as skin irritation and sometimes allergic reactions, while providing their benefits.
Retinoids are a class of natural and synthetic compounds that include vitamin A and its related chemicals. Retinoids like retinoic acid, retinol (and vitamin A precursors), and their derivatives are used in numerous skin care products, and serve as the “gold standard” active ingredients for “anti-aging” skin care and acne treatment. Retinoids affect the dermis, the epidermis and skin appendices, enhance skin health and wellness, decrease fine lines, even skin color, improve texture, tighten pores, and stimulate blood flow and collagen production. Retinoids are also very effective anti-acne compounds and have efficacy in treating psoriasis.
Unfortunately, many individuals cannot tolerate retinoids because they can be irritating and drying. Retinol and retinoic acid and their derivatives induce redness, scaliness, itching, burning and drying in a dose-responsive manner. Increasing retinoids concentrations, therefore, would enhance epidermal and dermal benefits and reduce the signs of skin aging, but would also increase skin irritation.
The cosmetic and pharmaceutical industries are constantly seeking solutions to reduce topical agent-induced irritation, including retinoid-induced irritation, which would enable (i) an increase in the effective dose of the topical agent without inducing the irritating side effects, or (ii) a reduction in the effective dose of the topical agent without reducing the cosmetic or therapeutic efficacy while reducing the irritating side effects.